Passengers were stranded for several hours after a 13-year-old boy managed to board a US bound-flight from the United Kingdom without a ticket.

The breach was discovered after cabin crew asked to see the unaccompanied minor’s boarding pass on a British Airways flight to Los Angeles on July 14, The Independent reports.

“When it became clear that he did not have the correct travel documentation, the entire flight was de-planed and passengers had to go through security again.”

The Metropolitan Police confirmed the child did not have any travel documents.

“The boy was an unaccompanied minor,” said a spokesperson. “He is not a UK national.”

Police believe the boy arrived at Heathrow as a transit passenger.

“As a security precaution, passengers de-planed following a discussion between police and the captain,” the spokesperson added.

“He remains in the care of police and liaison continues with the immigration services.”

Passenger Rachel Richardson tweeted “So I survived my six-hour wait at Heathrow but am now delayed on the tarmac because a young boy made his way onto our plane – BA269 – without a ticket.

“Big security breach. So much fun for everyone onboard.”

So I survived my six hour wait at Heathrow but am now delayed on the tarmac because a young boy made his way onto our plane - BA269 - without a ticket. Big security breach. So much fun for everyone on board We were meant to take off at 4.15pm. It’s nearly 6pm

— Rachel Richardson (@RachelARich) July 14, 2019

British Airways said it had apologised to customers for the “delay to their flight after an issue during boarding.”

“The safety and security of our customers and crew is always our top priority and everyone who had boarded the aircraft had been subject to security checks.

“We conducted additional precautionary screening as soon as this issue came to light and we are assisting the police with their enquiries,” a spokesperson said.

A Heathrow spokesperson confirmed the airport is working with police and the airline to understand how an unauthorised passenger boarded the incorrect aircraft, according to The Independent.

“The individual did not represent a security risk and, purely as a precaution, the aircraft in question was re-screened and has since departed,” they said. “We apologise for the disruption and will continue working closely with the authorities and our airline partners to keep the airport safe.”